1. Field of the Invention
The present invention relates to continuous mining machines for excavating a longitudinal shaft or tunnel underneath the surface of the earth. In particular, the invention relates to such machines which have improved cutting means for advancing the shaft, wherein the cutting means moves in an arcuate path from one side of the machine to the other at the forward end of the machine. The invention further relates to such machines which have improved transport means for advancing the machine over the floor of the shaft such that the machine can be abruptly turned in place to change the direction of advance of the machine to any desired, new direction.
2. State of the Art
All continuous mining machines of the prior art can be categorized as full face machines or partial face machines. Full face machines sump into the face of the excavation by moving the whole machine forward to advance the cutting means into the face of the excavation by the depth of the cutting means. Full face machines of the prior art may utilize angled advance of the cutting means into the advancing face of the excavation or they may sump the cutting means perpendicularly into the face. After the cutting means has been sumped into the face of the excavation, it is then moved sideways and up and down to extract the intended width and height of the shaft which is being excavated. The main frame on which the cutting head is mounted remains in place until the cutting depth of the advancing face has been fully extracted. The machine is then moved one web forward, and the cutting cycle is repeated. Partial face machines are similar in most respects to full face machines, but can only cut approximately their own width at one time. The width of these machines is less than that of the advancing face of the excavation. Thus it is necessary to move the partial face machines repeatedly forward, backward and sidewards in order to open the full width of the advancing face of the excavation.
Long boom type cutting heads, usually mounted on Caterpillar type tractors, have commonly been used in mining machines of the prior art. The boom moves up and down and laterally back and forth to extract the face of the shaft or tunnel being excavated. Drilling or boring type cutting heads that can be moved up and down and laterally back and forth relative to the main frame of the machine have also been used on machines of the prior art. As mentioned previously, full face machines extract the full width of the shaft or tunnel with each advance of the machine, whereas partial face machines must be maneuvered back and forth to extract the full width of the shaft or tunnel.
Full face machines suffer from various disadvantages depending on their specific design. Various disadvantages are inherent in all full face machines of the prior art which hamper efficient operation of the machines and restrict the machines from being true continuous mining machines.
The necessity to move the main frame of the machines during the sumping portion of the extraction cycle and the massive size of the machines prevent integration of roof support functions, such as roof bolting, simultaneous with the mining function. The massive size of the cutting units as well as the machines as a whole do not allow roof support operations to be performed simultaneously with the mining operations even in the portion of the extraction cycle when the main frame of the machines is stationary.
Further, the massive dimensions of the machines of the prior art do not allow roof support operations to be readily performed at desired proximity of the advancing face of the excavation even when the mining function of the machines is idled. As a result, the mining machine must not only be idled, but it must be moved back from the face of the excavation for roof support operations to be performed.
Experience has shown that so called continuous miners of the prior art deserves that name at most only about seventy percent of the time. They remain idle the rest of the time due to roof support tasks that must be carried out while the machines are idle.
Another disadvantage of the prior art machines is that their design and massive dimensions do not allow for ease of turning the machines into different cutting directions, e.g., into crosscuts. Considerable maneuvering and/or costly disassembly is required if a change in cutting directions is desired. The maneuvering of the massive machine often results in miring of the machine into the floor of the excavation. If the machine becomes mired in the floor, extensive time and effort is required to extricate the machine from the depression that it itself has produced. The inefficient and time consuming operations involved in turning the mining machines of the prior art in a new direction, such as when a crosscut is to be made, when added to the idle time required for roof support functions greatly restrict the productivity of the machines.
Uneven and irregular cutting patterns inherent with the prior art machines further create irregular ribs at the sides of the excavation. The irregular ribs represent injury hazards, and work intensive cleanup is often required because of sloughing of the ribs. In addition, gas and dust control is minimal with the prior art machines. The design of the machines are not conducive to controlling gas and dust created in the area of the cutting operation so as to limit migration of dust and gas from the area of the cutting operation.
Partial face machines, though having somewhat higher mobility than full face machines because of their somewhat reduced size, still have all the disadvantages of full face machines as discussed above. Integration of roof support operations with the mining operations is unfeasible because of the excessive maneuvering of the machines during mining. The almost constant maneuvering of the partial face machines results in excessive damage to the floor of the excavation. This causes severe utilization problems when the floor becomes damaged to the point that the machine becomes mired and stuck. High maintenance demands, especially in the presence of water, are made in freeing mired machines as well as repairing the floor of the excavation for other purposes.
Examples of so called continuous mining machines as disclosed in the patent literature are shown in the following U.S. Pat. Nos. 4,770,469; 4,740,037; 4,721,340; 4,641,889; 3,498,675; and 2,711,634. These patents were found as a result of a search that was made preliminary to the filing of the application for patent of the present invention. These patents do not show or even remotely suggest the novel improvements of the present invention.
3. Objectives
A principal objective of the invention is to provide a novel mining machine that approaches closely a true continuous mining machine which is capable of integrating roof supporting operations with the mining function, so that roof support and mining operations can be carried out substantially simultaneously.
A particular objective of the present invention is to provide such a machine which has cutter means that moves in an arcuate motion about the forward end of the machine and from one side of the machine to the other side to cut an advance cut of set depth in the face of the excavation while the main frame of the machine remains stationary, such that roof supporting functions can be undertaken from the main frame of the machine simultaneously with the cutting of the advance cut in the face of the excavation.
Another objective of the present invention is to provide such a novel mining machine in which the cutter means moves in an arcuate motion about the forward end of the machine and is further adapted to move in a linear motion parallel to the direction of advance of the excavation when the cutter head is at the opposite sides of the machine, whereby substantially straight ribs can be cut at the sides of the excavation.
A further objective of the present invention is to provide such a novel mining machine that is adapted to cut a full width in the advancing face of the excavation without requiring elaborate maneuvering other than forward movement to accomplish the next subsequent cut in the advancing face of the excavation.
A still further objective of the present invention is to provide such a novel mining machine having means to facilitate quick, abrupt changes in the direction of mining, such as to develop a crosscut entry, without requiring multiple forward and reverse movements of the machine so as to avoid the waist of time in accomplishing the change in direction as well as to avoid undue damage to the floor of the excavation caused by such repeated forward and reverse movements.
An additional objective of the present invention is to provide such a novel mining machine having means for providing temporary support to the roof of the excavation immediately above the mining machine while also allowing installation of roof bolts as closely as possible to the advancing face of the excavation.
Another objective of the present invention is to provide such a novel mining machine having means for separation of the mining and working areas on the machine with a protective divider to provide for dust and gas control in the working areas of the machine.